In the early 1840s Joseph Smith proposed to Mary Elizabeth Rollins Lightner. Elizabeth recorded “Joseph said I was his before I came here and he said all the Devils in hell should never get me from him.” Joseph further told her, “I was created for him
before the foundation of the Earth was laid.” (Todd Compton. In Sacred Loneliness pg 212 italics added) This may have been the
early beginnings of a pre-existence forming in Joseph Smith cosmology. His words were similar to some of his other wives. For instance in 1841 Joseph made it known to Zina Diantha Jacobs (Huntington Young) that the Lord, “had made it known to him that Zina was to be his wife.” (Ibid. pg 80 italics added)

Perhaps these and other 19th century marriages helped plant the idea in the Mormon psyche that people met and fell
in love in heaven, promising to marry once on earth, foreordained if you will.